Drew Stubbs led off the 11th with a single off Tyler Clippard (1-1) and went to second one out later on Zack Cozart's hit. Votto then sliced a 2-0 pitch over the head of Nationals left fielder Mark DeRosa to the wall, scoring both runners.
Scott Rolen chased home Votto on with an RBI single and the Reds avoided a four-game sweep at the hands of the Nats.
Ryan Ludwick cracked a grand slam and Cozart finished with three hits for the Reds.
Ian Desmond went 3-for-5 with a pair of RBI for Washington, which fell to 7-3 to start the season.
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